Chilblain-like acral lesions due to C. pneumonia infection during pandemic period

ABSTRACT

Introduction: Increase in cases with chilblain-like acral lesions has been observed during the pandemic period. Epidemiological data suggest that children have different immunological responses to SARS-CoV-2 virus, which can cause mild respiratory illness but more frequently involve other organ systems. Co-infection of SARS-CoV-2 with Chlamydia or Mycoplasma pneumoniae has been described both in adults and pediatrics (1). Objectives: To analyze clinical features, laboratory and instrumental findings of a group of patients with chilblain-like lesions during SARS-CoV-2 pandemic period. Methods: Retrospective analysis of 4 patients with chilblain-like lesions. Results: We present 4 patients with chilblain-like acral lesions (2 female and 2 male). The median age was 15.5 years (13 to 16 years old). Two patients had lesions only in toes whilst others had both hand and feet perniosis. All patients had no laboratorical signs of inflammation (CRP, ESR, WBC, neutrophil, and lymphocyte count were in normal range) and markers for rheumatic and connective tissue diseases (cryoglobulins, antinuclear antibodies, anti-double-stranded DNA antibodies, antineutrophil cytoplasmic antibodies, rheumatoid factor) were negative. Levels of serum complement C3 (mean value 0.775 g/l) and complement C4 (mean value 0.1425 g/l) was reduced in all cases. Two patients had positive Chlamydia pneumonia antibodies (IgM titers of >12 were defined as positive), others were not tested. The first patient had lesions in toes and for the second patient, both hands and feet were damaged. All patients underwent ultrasound of affected sites. One of 4 patients was diagnosed with reactive arthritis in metatarsophalangeal joints in ultrasound and MRI. There was no epidemiological anamnesis or clinical manifestation or any evidence of SARS-CoV-2 infection (SARS-CoV-2 antibodies were negative) for all patients. Also, there was no anamnesis of any respiratory tract symptoms or diagnosed infection in the last 4 months in all patients. Patients with C. pneumoniae IgM antibodies positive were given a course of clarithromycin. Despite the prescribed course of antibiotics, the skin lesions remained. One patient with arthritis was treated with NSAIDs. Others resolved by themselves without requiring any treatment. Conclusion: Chilblain-like lesions in the skin can be one of the signs of previous SARS-CoV-2 infection despite negative virus antibodies (2). Possible hypothesis is a high production of type I interferon (IFN) associates with early viral control and suppression of antibody production. A strong IFN response can cause skin manifestations (3). Coinfection with other atypical bacteria can intensify immune complexes formation and skin injury (4). This phenomenon can be observed with low levels of C3 and C4 in blood samples.